The plane wave packet (PWP) and nearside-farside approaches are combined, in order to obtain time-dependent differential cross-sections (DCSs) describing the scattering of a plane wave packet over the full theta = 0 -> 360 degrees sphere. This produces a better separation of different reaction mechanisms than previous theta = 0 -> 180 degrees PWP calculations. Application to the He + H-2(+) reaction separates clearly the direct and time-delayed mechanisms, showing that the latter (caused by decay of HeH2+ scattering resonances) does not begin until the HeH2+ complex has rotated by over half a revolution, and then continues until the HeH2+ has described almost an entire revolution. The resulting nearside-farside interference from this decay dominates the (energy-domain) DCS. (c) 2005 Elsevier B.V. All rights reserved.